I've just got a meteorb sorc up and running Nightmare Meph with really ghetto gear and a perfect map.
One of my runs went like this:
Down the stairs. Teleport to the right-hand corner of the big room. No Bremm Sparkfist around. I teleport across the right side (Wyand Voidbringer's) to Mephisto, my merc dies, and I retreat to do the moat trick on the left side. I'm hit by Bremm's Conviction aura, and start orbing his pack. Blood lord group attacks from below. Hydras, meteors, fireballs, and sparks appear everywhere, and I spam orbs while teleporting around randomly so that I don't stay in the same place.
The monsters all died, and I stayed above 3/4ths health the whole time, but I didn't feel like the situation was under control. I don't like things to be that chaotic.
Do people take time to park Bremm's pack in the bottom of the room while they moat Mephisto on the right? That's what I will try doing for now, but I'd like to get some advice. I tried several searches but found nothing relevant.
EDIT: Hmmm, funny. I meant to post this in the Single Player forum, but this one works, too! Oops/hooray!!? =]